Rishi: Yājñavalkya (traditional White Yajurveda attribution; specific r̥ṣi not always separately assigned for VS prose-like formulas).
Devata: Yajña / Prajāpati (functional deity: the Sacrifice as divine totality; with prajā as the desired fruit).
Chandas: Yajus (non-metrical sacrificial formula; not a fixed ṛc-meter).
Samhita Patha (Devanagari)मा भे॒र्मा संवि॑क्था॒ अत॑मेरुर्य॒ज्ञोऽत॑मेरु॒र्यज॑मानस्य प्र॒जा भू॑यात् त्रि॒ताय॑ त्वा द्वि॒ताय॑ त्वैक॒ताय॑ त्वा
Transliterationmā bhēr mā saṃvīkthā́ atamērur yajñó ’tamērur yajamānasya prajā́ bhūyāt tritā́ya tvā dvitā́ya tvā ekatā́ya tvā
Translationஅஞ்சாதே; கலங்காதே. யாகம் அசையாமல் இருக்கட்டும்; யஜமானனின் சந்ததியும் அசையாமல் இருக்கட்டும். மூன்றாம் (நிறுத்தல்)க்காக உன்னை; இரண்டாம் (நிறுத்தல்)க்காக உன்னை; முதல் (நிறுத்தல்)க்காக உன்னை.
Padapatha (Word Analysis)मा । भेः । मा । सम्-विक्थाः । अत-मे॒रुः । य॒ज्ञः । अत-मे॒रुः । यज॑मानस्य । प्र॒जाः । भू॑यात् । त्रि॒ताय॑ । त्वा । द्वि॒ताय॑ । त्वा । एक॒ताय॑ । त्वा
Word by Wordसंविक्थाःbe not confounded / do not be distressed अतमेःhaving the ‘Atameru’ (as its meru/peak); ‘with Atameru as summit’ अतमेःhaving the ‘Atameru’ (as summit) यजमानस्यof the sacrificer भूयात्may it be / may it become त्रितायfor Trita / to the third (one) द्वितायfor Dvita / to the second (one) एकतायfor Ekata / to the first (one) / to oneness 
Entities MentionedY
Yajña (the Sacrifice as divine totality) Viniyoga (Ritual Application)